There is considerable interest in so-called swellable clays which can be used, inter alia, in the preparation of pillared clays which are considered promising alternatives to zeolites, in particular since larger pores can be obtained than available with zeolites, provided a proper choice of pillaring materials has been made.
Saponites belong to the family of smectic clays, i.e. swellable compounds, which also include montmorillonites, hectorites, nontronites and beidellites. Both fluorine-containing and fluorine-free saponites are known.
An interesting structural feature concerning saponites, normally represented by the formula EQU A.sub.x/n.sup.n+ [(Mg.sub.3)(Si.sub.4-x Al.sub.x)O.sub.10 Z.sub.2 ].mH.sub.2 O (I)
wherein A usually represents lithium, sodium or calcium, x represents a value between 0.05 and 0.95, n represents the valence of A, Z represents a fluorine and/or a hydroxyl group and m has typically a value between 2 and 5, is that magnesium is situated in the octahedral layer at the centre of the triple layer sheet of the smectic clay.
A novel class of saponite-derivatives has now been found which have interesting properties both as catalyst carriers and under certain conditions as catalysts themselves. The saponite-derivatives according to the present invention can moreover also be prepared under rather mild process conditions which widely enlarges their applicability.